Ultraviolet germicidal irradiation system

ABSTRACT

A modular germicidal light grid system for use inside an air treatment apparatus that has a plenum in which a stream of air is enclosed. The system comprises at least one elongate member and at least one lamp assembly. Each lamp assembly comprises a housing defining at least one socket and is mounted to one elongate member at a predetermined position. The system further comprises at least one linear germicidal light source. Each light source has a longitudinal axis and a distal end constructed and arranged to mount within one socket of the housing. The elongate member is mounted within the plenum and the lamp assembly is mounted to the elongate member such that the longitudinal axis of the light source extends therein the stream of air and is positioned at an acute light angle relative to the direction of flow of the stream of air.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/742,035, filed Jan. 15, 2013; which is a continuation of U.S.application Ser. No. 13/229,293, filed Sep. 9, 2011, which is now U.S.Pat. No. 8,354,060, issued Jan. 15, 2013; which is a continuation ofU.S. patent application Ser. No. 10/932,997, filed Sep. 2, 2004, whichis now U.S. Pat. No. 8,038,949, issued Oct. 11, 2011 The disclosure ofeach of the above-referenced applications are hereby incorporated hereinby reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to an ultraviolet germicidalirradiation system for sterilization of microorganisms in variousapplications. More specifically, the present invention relates to anultraviolet germicidal irradiation system for use in residential,commercial, and industrial heating, ventilation, and air-conditioning(“HVAC”) applications.

BACKGROUND OF THE INVENTION

Contaminated air in buildings and homes is now an international issue.Certain airborne contaminants cause widespread discomfort and healthproblems, leading to absenteeism from school and work, as well asreduced productivity. Healthy and productive indoor environments wouldsave billions of dollars in health care costs, lost work time, overalloutput and possible litigation.

Of the many contaminants found in indoor air, bioaerosols are regardedas the leading cause of allergies and other maladies referred to as SBS(Sick Building Syndrome) and BRI (Building-Related Illness). Bioaerosolsare airborne products that include microorganisms, their fragments andspores, metabolic gases, and other toxins and waste products. Numerousstudies have found high concentrations of these bioaerosols both in airhandling equipment and the interiors they serve.

Airborne and surface microorganisms include pathogens, allergens, andtoxins. Included in the category of pathogens are viruses, bacteria, andmold, which could cause measles, chicken pox, Legionnaires disease,aspergillosis, tuberculosis, and other infectious disease. Bacteria andmold are also classified as allergens because they can cause allergicrhinitis, asthma, humidifier fever and hypersensitivity pneumonitis.Toxins include mycotoxins and endotoxins, which can cause toxic andallergic reactions, irritations, and odors. Among allergens, mold andmold products are probably the most common worldwide.

Allergy tests universally bear out this phenomenon. In HVAC equipment,mold can proliferate year-round. With most individuals, prolongedexposure to mold and mold products initiates the release of histamines,causing inflammation of mucous membranes, which can be followed bycongestion, breathing difficulties, asthma and other respiratorycomplications.

Conventional HVAC systems are an ideal source and conduit for the originand/or spread of microorganisms. Their environments are especiallyconducive to amplifying molds and some bacteria. The fans of the HVACsystem disseminate and/or recirculate system, space andoccupant-generated microorganisms room to room and person to person.Conventional filtration assemblies of such HVAC systems are compromisedbecause growth typically occurs downstream of filters, which allowsmicroorganisms to seed in the ductwork and travel to and throughout theoccupied space. Additionally, viruses and many bacteria are too small tobe captured by a common air filter.

Traditional bioaerosol controls tend to be impractical, toxic,detrimental to equipment operation, and costly. Hence, the industry hasturned to ultraviolet germicidal irradiation (“UVGI”) for thesterilization of microorganisms. In HVAC systems, the application ofUVGI in the air handling unit cooling coil and filter assemblies iseffective in reducing the number of microorganisms. Additionally, theconstant irradiation exposure has been found to be effective atcontrolling fungal growth.

Microbes are uniquely vulnerable to the effects of light at wavelengthsat or near 2537 Angstroms, due to the resonance of this wavelength withmolecular structures. A quantum of energy of ultraviolet light at thesewavelengths possesses an amount of energy sufficient to break organicmolecular bonds, which damages the cellular structure of themicroorganisms.

The ultraviolet component of sunlight is the main reason microbes die inthe outdoor air. The die off rate in the outdoors varies from onepathogen to another, but can be anywhere from a few seconds to a fewminutes in order to kill 90 to 99% of viruses and contagious bacteria.Spores and some environmental bacteria tend to be resistant and cansurvive much longer exposures. UVGI systems use much more concentratedlevels of ultraviolet energy than are found in sunlight.

The kill rate of pathogens and other microorganisms using UVGI dependson several factors, including UVGI intensity, the number ofmicroorganisms present, and the amount of time the microorganisms arepresent in the UVGI zone, or dwell time. Generally, kill rate increasesas the UVGI intensity is increased and/or the dwell time is increased.

SUMMARY

The invention described herein is a germicidal light grid system. In oneexample, the light grid system is positioned inside a plenum. The lightgrid system can be positioned adjacent to a cooling apparatus, such as,for example, an evaporative cooling coil. One can appreciate that such alight grid system is not limited for use inside a plenum, nor is itlimited when used inside of a plenum to being positioned adjacent tocooling apparatuses. For instance, the light grid system can be used inplenums adjacent to air filtration banks, air intake vents, air mixingjunctions, and/or plenum transition areas.

The light grid system of the present invention comprises at least oneelongate member, at least one lamp assembly, and at least one germicidallight source. The at least one elongate member is mounted within aplenum in which a stream of air is entrained therein. In one aspect, theat least one elongate member can be connected to a portion of theplenum.

In one example of the light grid system, the at least one lamp assemblyis mounted at a predetermined position on a portion of one of theelongate members. The predetermined position is operator selectable andcan include any portion of the elongate length of the elongate member.Each lamp assembly comprises a housing defining at least one socket thatextends at an acute angle relative to a transverse axis of the housing.The linear light source has a longitudinal axis and a distal end that isconstructed and arranged to releasably mount within one socket of thehousing. In use, each light source extends therein the stream of airsuch that the longitudinal axis of the light source is positioned at anacute light angle relative to the direction of flow of the stream ofair.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the preferred embodiments of the presentinvention will become more apparent in the detailed description in whichreference is made to the appended drawings wherein:

FIG. 1 is a top elevational view of one embodiment of the germicidalirradiation system of the present invention mounted therein a plenum.

FIG. 2 is a front elevational view of the germicidal irradiation systemof FIG. 1.

FIG. 3 is a side elevational view of the germicidal irradiation systemof FIG. 1.

FIG. 4 is a perspective view of a portion of an exemplified elongatemember of a support assembly of the present invention.

FIG. 5 is a cross-sectional view of the elongate member of FIG. 4 takenacross section 5-5.

FIG. 6 is a top elevational view of one embodiment of a lamp assembly ofthe germicidal irradiation system of the present invention spaced from across-sectional view of an exemplified elongate member, and showing ahousing, at least one linear light source mounted therein sockets of thehousing, the linear light source being angled at an acute angle α withrespect to the transverse axis of the housing.

FIG. 7 is a front elevational view of the lamp assembly of FIG. 6showing a ballast device disposed therein an internal cavity of thehousing.

FIG. 8 is a side elevational view of the lamp assembly of FIG. 6,showing a flange member adapted to mount within a portion of anexemplified elongate member.

FIG. 9 is a top elevational view of an alternative embodiment of a lampassembly of the germicidal irradiation system of the present inventionspaced from a cross-sectional view of an exemplified elongate member,and showing a housing, at least one linear light source mounted thereinsockets of the housing, the linear light source being angled at an acuteangle α with respect to the transverse axis of the housing.

FIG. 10 is a front elevational view of the lamp assembly of FIG. 9showing a ballast device disposed therein an internal cavity of thehousing.

FIG. 11 is a side elevational view of the lamp assembly of FIG. 9,showing a flange member adapted to mount within a portion of anexemplified elongate member.

FIG. 12 is a top elevational view of an alternative embodiment of a lampassembly of the germicidal irradiation system of the present inventionspaced from a cross-sectional view of an exemplified elongate member,and showing a housing, a linear light source mounted therein a socket ofthe housing, the linear light source being angled at an acute angle αwith respect to the transverse axis of the housing.

FIG. 13 is a side elevational view of the lamp assembly of FIG. 12,showing a flange member adapted to mount within a portion of anexemplified elongate member.

FIG. 14 is a front elevational view of the lamp assembly of FIG. 12showing a ballast device disposed therein an internal cavity of thehousing.

FIGS. 15-20 are top, front, and side elevational views of exemplaryconstructions of the germicidal irradiation system of the presentinvention showing the linear light source being positioned an the acuteangle α with respect to the transverse axis of the housing and showingthe lamp assembly being mounted to the elongate member such that thelongitudinal axis of the light source extends therein the stream of airat an acute light angle relative to the direction of the flow of thestream of air entrained in the plenum. In one aspect, the longitudinalaxis of the light source is positioned at an acute light angle θrelative to the common plane formed by a first elongate member and asecond elongate member of a support assembly. In one aspect, the commonplane formed by the first and second elongate members is substantiallytransverse to the direction of the flow of the stream of air.

FIG. 21 are perspective views of an exemplary fastener and planar memberfor connecting the housing of the light assembly to an elongate member.

FIG. 22 is a perspective view of one embodiment of a mount forconnecting a first elongate member of the support assembly to a portionof a second elongate member of the support assembly.

FIG. 23 is a perspective view of a flange member of a housing of thelight assembly of the present invention.

FIG. 24 is a top elevational view of an alternative embodiment of a lampassembly of the germicidal irradiation system of the present inventionspaced from a cross-sectional view of an exemplified elongate member,and showing a first body, a second body, and an elongate conduitextending therebetween, and showing a linear light source mountedtherein a socket of the second body of the housing, the linear lightsource being angled at an acute angle α with respect to the transverseaxis of the housing.

FIG. 25 is a side elevational view of the lamp assembly of FIG. 24,showing a flange member adapted to mount within a portion of anexemplified elongate member.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the followingexemplary embodiments that are intended as illustrative only sincenumerous modifications and variations therein will be apparent to thoseskilled in the art. As used herein, “a,” “an,” or “the” can mean one ormore, depending upon the context in which it is used. The preferredembodiments are now described with reference to the figures, in whichlike reference characters indicate like parts throughout the severalviews.

Ranges may be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment.

FIGS. 1-3 illustrate one embodiment of a modular germicidal light gridsystem 10. This embodiment of the light grid system is designed for useinside a plenum 2 in which a stream of air 4 is entrained and flows in apredetermined direction. The light grid system 10 can be positionedadjacent to a cooling apparatus 6, such as, for example, an evaporativecooling coil. One can appreciate that the light grid system 10 of thepresent invention is not limited for use inside a plenum, nor is itlimited when used inside of a plenum to being positioned adjacent tocooling apparatuses. For instance, the light grid system 10 of thepresent invention can be used in plenums 2 adjacent to air filtrationbanks, air intake vents, air mixing junctions, and/or any plenumtransition area.

In one aspect, the light grid system 10 comprises at least one elongatemember 20, at least one lamp assembly 50, and at least one lineargermicidal light source 70. The elongate member 20 is positioned withinthe plenum 2. Each lamp assembly 50 comprises a housing 52 having atransverse axis, as is shown in FIGS. 6-14. In one example of the lightgrid system 10, the transverse axis of the housing 52 is substantiallyperpendicular to a plane transverse to the direction of flow of thestream of air 4. However, the transverse axis of the housing 52 can bepositioned in any desired relation to the direction of flow of thestream of air 4. The housing 52 defines at least one socket 54 thatextends at an acute angle α relative to the transverse axis of thehousing. A portion of the housing 52 of each lamp assembly isconstructed and arranged to mount to a portion of the at least oneelongate member 20 at a predetermined position that is operatorselected. The predetermined position can, as one will appreciate, be anyportion of the elongate length of the elongate member, as desired.

Each linear light source 70 has a longitudinal axis and a distal end 72constructed and arranged to mount within one socket 54 of the housing.As one will appreciate, it is contemplated that the light source can beremoveably replaced as maintenance requires. In one aspect, the at leastone lamp assembly 50 is mounted to the at least one elongate lightmember 20 such that the longitudinal axis of the at least one lightsource 70 extends therein the stream of air and is positioned at anacute light angle relative to the direction of the flow of the stream ofair 4.

In one aspect, the at least one elongate member forms 20 a part of amodular support assembly 22. In use, the modular support assembly 22 ofthe present invention provides for the economical and efficientconstruction of a support structure that can be dimensioned as desiredto fit within the particular physical dimensions of the plenum 2. Priorgermicidal light systems required a “custom fit” preparation of asupport structure that increased the expense of the installed airtreatment system and the lead time required for installation (for theactual physical construction of a “custom” structure).

In one example, the modular support assembly 22 of the present inventioncomprises at least one elongate first member 24 and at least oneelongate second member 26 positioned substantially perpendicular to theelongate first member. One or more of the elongate first or secondmembers 24, 26 can be connected to a portion of the plenum 2. In oneaspect, the at least one elongate first member 24 and the at least oneelongate second member 26 are positioned within a common plane. In oneaspect, the housing 52 of the light assembly 50 can be mounted to theelongate member 24, 26 such that the transverse axis of the housing 52is substantially perpendicular to the common plane of the elongate firstand second members.

In one embodiment, the elongate second member 26 can be constructed from1⅝″ three walled strut type channel UL electrical raceway material. Asone will appreciate, the elongate first member 24 can also beconstructed from the same material. Using conventional raceways that canbe mounted to each other with conventional fasteners and/or mountsallows for expedient construction of the support assembly. As one willappreciate, these are merely representative examples of constructionmaterials and methodologies. For example, the elongate first and secondmembers 24, 26 can be connected in any of a number of ways, such as, forexample, with conventional fasteners.

In one aspect, the at least one linear germicidal light source 70extends such that the longitudinal axis of the light source ispositioned at an acute light angle θ, relative to the common planeformed by the first and second elongate members 24, 26. In one aspect,the common plane formed by the first and second elongate members 24, 26is substantially transverse to the direction of flow of the stream ofair 4. The linear light sources 70 can be, for example, 22″ double arclength 4-pin germicidal lamps, such as the TUV PL-L 55W/HF made byPhilips™. However, as one skilled in the art will appreciate, anyelongate ultraviolet germicidal lamp can be used.

In one example of the system, the preferred acute light angle θ is about10° to less than about 90°. More preferably, the acute light angle θ isbetween about 20° to about 80°. Even more preferred, the acute lightangle θ is between about 30° to about 70°. Still more preferred, theacute light angle θ is about 30°, or alternatively, about 45°.

In one example, at least one elongate first member 24 is spaced atpredetermined distance from the cooling apparatus 6. In another aspect,at least one elongate second member 26 can be positioned at the samepredetermined distance from the cooling apparatus 6, or, alternatively,can be at a different predetermined distance. In one example of thelight grid system, the predetermined distance is preferably betweenabout 3″ and about 24″. More preferably, the predetermined distance isbetween about 5″ and about 20″. Still more preferred, the predetermineddistance is about 18″. Alternatively, the predetermined distance isabout 12″. In still another alternative aspect, the predetermineddistance is about 6″.

As is depicted in FIG. 1, in one example of the light grid system 10each socket 54 of the housing 52 has a longitudinal axis that isoriented rearwardly away from the cooling apparatus 6. In yet anotherexample, each socket 54 of the housing 52 has a longitudinal axis thatis oriented forwardly toward the cooling apparatus 6. In still anotherexample, the light grid system 10 has at least one socket 54 orientedrearwardly away from the cooling apparatus 6 and at least one socket 54oriented forwardly toward the cooling apparatus 6.

As shown in FIGS. 10-13, in one embodiment, the light grid system 10 ofthe present invention further comprises a power supply 80 and at leastone ballast device 82 electrically coupled to the power supply and theat least one socket 54 of the housing. In one aspect, the housing ofeach light assembly can define an internal cavity 56 that is sized andshaped for the at least one ballast device 82 to be disposed therein. Inanother example, the ballast device 82 is located at a remote locationspaced from the housing. The ballast device 82 can be electricallycoupled to the power supply 80 conventionally, for example, by usingconventional 3 or 6 stranded electrical wires.

One example of the ballast device 82 is a solid-state, non-potable, highfrequency ballast operating at about either 120 or 277 volts AC and atabout 50 to 60 Hz. For exemplary lamp assemblies 50 with two germicidallight sources, a single uniform ballast allows for subsequent simplicityfor inventory and change requirements by the end user. In one aspect ofthe ballast device 82, the ballast device is self-regulating with directcurrent output. In one aspect, the ballast device 82 for the exemplarytwo light source lamp assembly 50 can deliver up to about 110 watts toeach lamp or about 220 watts total. In one aspect, the ballast device 82for an exemplary one light source lamp assembly 50 can deliver up toabout 140 watts to the lamp.

In practice, the housing that contains the ballast device 82 can bepre-wired for connection to the remote power supply 80. In this example,the ballast device 82 can include a wiring assembly 84 that extends fromthe internal cavity 56 of the housing through a port 58 defined in thehousing 52. In this example, the support assembly 22 and the at leastone lamp assembly 50 mounted thereto, can be constructed completely bythe installer. Then, after the construction is complete, an electriciancan electrically connect the wiring assembly 84 extending from themounted lamp assemblies 50 to the power supply by coupling the wiringassembly 84 to the electrical wire 81 that extends to the power supply80.

FIGS. 6, 9 and 14 show an example of the lamp assembly in which the lampassembly 70 is releasably mounted to the elongate member, for example, asecond elongate member 26, of the support assembly. As one willappreciate, having the lamp assembly 70 releasably attached to theelongate member 20 provides for convenient installation and disassembly.However, it will be appreciated that any number of attachment techniquesincluding providing permanent attachments are contemplated.

FIGS. 4 and 5 illustrate an example of the support assembly 22 in whichthe elongate second member 26 and/or the elongate first member 24defines a trough 30. Further, a portion of the housing 52 is sized andshaped for disposition within a portion of the trough 30 of the elongatemember 20. In one example, the elongate second member 26 can have asubstantially U-shape in cross-section. As one skilled in the art willnote, the elongate member 20 can have any number of variedcross-sectional shapes, including, for example, a V-shape, a C-shape,and the like. In one aspect, a portion of the housing 52 is adapted fora friction fit within the portion of the trough 30 of the elongatemember 20.

In this embodiment, the trough 30 acts as a conduit that is adapted fordisposition of wiring that couples the power supply 80 to the ballastdevice 82 and subsequently to the at least one socket 54 of the housing.Additionally, as exemplified in FIG. 23, a closure strip 29 can beprovided to seal the open portion of the trough 30 after wiring of thelight grid system 10 is complete to seal the inside of the trough fromthe ambient environment. Thus, the formed conduit acts as an electricalraceway that enables the system assembler to conceal any necessaryelectrical wires.

FIGS. 4 and 5 also show an example wherein the elongate second member 26defines a trough 30 that has a pair of opposing, longitudinallyextending, edges 32 that bend inwardly to form a pair of opposing maleprotrusions 34. A portion of the housing 52 is sized and shaped fordisposition within a portion of the trough 30. In one aspect, theportion of the housing 52 defines an elongate flange member 60 having apair of longitudinally extending, opposing male protrusions 62. Theopposing male protrusions 62 of the flange member 60 are sized andshaped for overlying registration within the portion of the trough 30 ofthe elongate second member 26. As one will appreciate, the pair ofopposing male protrusions 62 of the flange member 60 can be adapted fora friction fit with the portion of the trough 30.

In one aspect, and as exemplified in the figures, the housing 52 ispositioned on an elongate second member 26 using a snap-fit connection.This configuration allows the independent installation of the supportassembly and lamp assembly to be constructed by non-electricallyqualified personnel such as mechanical contractors. Once the supportassembly 22 is constructed and the lamp assemblies 50 are mountedthereon, a second independent installation of the electrical componentscan be completed by qualified electrical contractors. Additionally, thesnap in feature used in this example allows the electrical contractor towire the lamp assembly without dismantling the housing 52. It alsoenables the end user to quickly remove and replace the lamp assembly.

Another example of the light grid system 10 is shown in FIGS. 4, 5 and21. Here, the pair of opposing male protrusions 34 of the trough 30 arespaced apart a predetermined distance. This predetermined distance, forexample, preferably can be between about ½″ and 2″. More preferably, thepredetermined distance is about ⅞″. In this example, the second elongatemember 26 further comprises a fastener 35 coupled to the housing 52 ofthe light assembly and a planar member 36 that defines a bore 37. Theplanar member 36 in this example has a dimension greater than thepredetermined distance and is sized and shaped for positioning within aportion of the trough 30. In this example, the fastener 35 and the bore37 are complementarily sized and shaped so that, in use, the fastenerengages the bore of the planar member to force a portion of the planarmember into contact with a portion of the pair of opposing maleprotrusions 34. This acts to secure the housing 52 of the light assembly50 in the predetermined position on the elongate member.

FIG. 22 illustrates one embodiment of a light grid system 10 in whichthe elongate second member 26 is slidably mounted to the elongate firstmember 24. This allows for rapid adjustment of the elongate secondmember with respect to the elongate first member should it be needed. Itis contemplated that the second elongate member can be releasably fixedto the first elongate member when the respective elongate members are attheir desired positions.

In an alternative embodiment of the lamp assembly 50, as shown in FIGS.24 and 25, the housing 52 of the lamp assembly comprises a first bodymember 51, an opposed second body member 53, and an extension conduit 55connected to and extending there between the first and second bodymembers. In one aspect of this embodiment, the extension conduit extendssubstantially coaxial to the transverse axis of the housing. The atleast one socket 54 is defined on the second body member 53. A portionof the first body member 51 of the housing 52 is constructed andarranged to mount to the portion of the elongate member as describedabove. In a further aspect, the first body defines the mutual cavity 56sized and sloped for the at least one ballast device 82 to be disposedtherein.

As noted above, the light grid system 10 of the present invention isconstructed to be positioned inside of a plenum 2 in which a stream ofair 4 is entrained. The stream of air has a direction of flow, in whichcontaminants and pathogens may exist. Positioning the light sources 70at an acute light angle, θ, relative to the common plane formed by thetwo elongate members, wherein the plane is perpendicular to direction offlow, increases the distance the contaminants and or pathogens musttravel inside of the UVGI zone. Thus, the microbial dwell time insidethe UVGI zone is increased, providing for a higher kill rate ofpathogens or contaminants as compared to a system in which θ is 0° or90°.

In another aspect, the angle at which the lamps are positioned isdetermined by the acute angle α, at which the socket extends relative tothe transverse axis of the housing. In one preferred example of thelight grid system, the acute angle α, is about 10° to less than about90°. More preferably, acute angle α is between about 20° to about 80°.Even more preferred, acute angle α is between about 30° to about 70°.Still more preferably, acute angle α is about 45°, or alternatively, isabout 60°.

Also disclosed is a performance standard for the measuring UVGI in agermicidal light grid system. These UVGI factors are calculated usingthe Inverse Square Law, which can be written

${I = \frac{S}{4\pi\; r^{2}}},$wherein I is the intensity of the influence, S is the source strengthand r is the distance from the source. For convenience, four levels ofperformance capability are disclosed. They are as follows:

-   -   Level 1: Minimum UVGI factor of 9.    -   Level 2: Minimum UVGI factor of 16.    -   Level 3: Minimum UVGI factor of 36.    -   Level 4: Minimum UVGI factor of 144.

The primary function of a system at Level 1 is the surface disinfectionof stationary devices. The secondary function of Level 1 is for thedeactivation of microbial agents in dynamic motion within a movingairstream. For the purpose of ease of discussion, in this and all of thefollowing discussions regarding performance capabilities, we assume thatthere are two germicidal light sources 70 per lamp assembly 50 and thatthe light sources used are the aforementioned Philips™ germicidal lamps.As such, in one example, the spacing of the germicidal light sources 70along the elongate second member 26 is about 48″ in order to maintain aUVGI factor of 9. Exemplary spacing between germicidal light sources 70on separate elongate second members 26 is about 24″ in order to maintaina UVGI factor of 9.

The primary function of Level 2 capability is for the deactivation ofmicrobial agents in dynamic motion within a moving airstream. Thesecondary function of Level 2 is for the disinfection of stationarysources, typically air-handling system components. In one example,vertical spacing of the germicidal light sources along the elongatesecond member is about 36″ in order to maintain a UVGI factor of 16.Exemplary spacing between germicidal light sources on separate elongatesecond members is about 18″ in order to maintain a UVGI factor of 16.

The primary function of Level 3 capability is for the deactivation ofmicrobial and pathogenic agents in dynamic motion within a movingairstream. The secondary function of Level 3 is for surface disinfectionof stationary devices, typically mission critical process filtrationair-handling system components. For example, vertical spacing of thegermicidal light sources along the elongate second member is about 24″in order to maintain a UVGI factor of 36. Exemplary spacing betweengermicidal light sources on separate elongate second members is about12″ in order to maintain a UVGI factor of 36.

The primary function of Level 4 capability is for the deactivation ofmicrobial and pathogenic agents in dynamic motion within an airstream.The secondary function of Level 4 is for surface disinfection ofstationary devices, typically mission critical process filtrationair-handling system components. In one example, vertical spacing of thegermicidal light sources along the elongate second member is about 12″in order to maintain a UVGI factor of 144. Here, the germicidal lamps onseparate elongate second members are crossed, with an example beingbetween them of about 6″ in order to maintain a UVGI factor of 144.

Although several embodiments of the invention have been disclosed in theforegoing specification, it is understood by those skilled in the artthat many modifications and other embodiments of the invention will cometo mind to which the invention pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is thus understood that the invention is not limited to the specificembodiments disclosed hereinabove, and that many modifications and otherembodiments are intended to be included within the scope of the appendedclaims. Moreover, although specific terms are employed herein, as wellas in the claims which follow, they are used only in a generic anddescriptive sense, and not for the purposes of limiting the describedinvention, nor the claims which follow.

What is claimed is:
 1. A modular germicidal light grid system for useinside a plenum downstream of a cooling apparatus, the systemcomprising: a support assembly comprising: at least one elongate firstmember; and at least one elongate second member mounted and positionedsubstantially perpendicular to the at least one elongate first member;and at least one lamp assembly, each lamp assembly constructed andarranged to mount to at least a portion of the at least one elongatesecond member of the support assembly, each lamp assembly comprising alinear germicidal light source having a longitudinal axis, wherein theat least one elongate first member and the at least one elongate secondmember are positioned within a common plane, and wherein the lineargermicidal light source of each lamp assembly extends such that thelongitudinal axis of the linear germicidal light source is positioned atan acute light angle relative to the common plane.
 2. The modulargermicidal light grid system of claim 1, wherein each lamp assemblyfurther comprises a housing defining at feast one socket for operative,mounting of the linear germicidal light source.
 3. The modulargermicidal light grid system of claim 2, wherein each light source has adistal end constructed and arranged to mount within one socket of thehousing.
 4. The modular germicidal light grid system of claim 2, whereinthe housing of each lamp assembly has a transverse axis, and wherein thetransverse axis of the housing is substantially perpendicular to thecommon plane.
 5. The modular germicidal light grid system of claim 4,wherein each socket of the housing extends at an acute angle relative tothe transverse axis of the housing.
 6. The modular germicidal light gridsystem of claim 4, wherein the housing of the at least one lamp assemblycomprises a first body member, an opposed second body member, and anextension conduit connected to and extending between the first andsecond body members, wherein the extension conduit extends substantiallycoaxial to the transverse axis of the housing, wherein the at least onesocket is defined on the second body member, and wherein a portion ofthe first body member of the housing is constructed and arranged tomount to the portion of the at least one elongate second member.
 7. Themodular germicidal light grid system of claim 2, further comprising apower supply and at least one ballast device electrically coupled to thepower supply and the linear germicidal light source.
 8. The modulargermicidal light grid system of claim 7, wherein the housing defines aninternal cavity, and wherein the at least one ballast device is disposedtherein the internal cavity.
 9. The modular germicidal light grid systemof claim 2, further comprising a power supply and at least one ballastdevice electrically coupled to the power supply and the at least onesocket of the housing.
 10. The modular germicidal light grid system ofclaim 9, wherein the housing defines an internal cavity, and wherein theat least one ballast device is disposed therein the internal cavity. 11.The modular germicidal light grid system of claim 2, wherein the atleast one elongate second member defines to trough, and wherein aportion of the housing is sized and shaped for disposition within aportion of the trough of the at least one elongate second member. 12.The modular germicidal light grid system of claim 1, wherein the atleast one lamp assembly is releasably mounted to the at least oneelongate second member of the support assembly.
 13. The modulargermicidal light grid system of claim 1, wherein at least one of therespective at least one elongate first and second members is connectedto a portion of the plenum.
 14. The modular germicidal light grid systemof claim 13, wherein at least one of the at least one elongate firstmember is connected to an interior surface of the plenum.
 15. Themodular germicidal light grid system of claim 13, wherein the at leastone elongate second member is slidably mounted to the at least oneelongate first member.
 16. The modular germicidal light grid system ofclaim 1, wherein the acute light angle is between about 10° to less thanabout 90 °.
 17. The modular germicidal light grid system of claim 1,wherein the acute light angle is between about 20° to about 80 °. 18.The modular germicidal light grid system of claim 1, wherein the acutelight angle is between about 30° to about 70 °.
 19. The modulargermicidal light grid system of claim 1, wherein the acute light angleis about 60 °.
 20. The modular germicidal light grid system of claim 1,wherein the acute light angle is about 45 °.